import math


def quadratic(a, b, c):
    pass

print('quadratic(2, 3, 1) =', quadratic(2, 3, 1))
print('quadratic(1, 3, -4) =', quadratic(1, 3, -4))
print('quadratic(0, 3, -4) =', quadratic(0, 3, -4))
print('quadratic(0, 0, -4) =', quadratic(0, 0, -4))
